A 14-year-old adolescent from Northern China was admitted to our hospital with a 10-year history of paroxysmal involuntary movement attacks. This symptom initially was noted at the age of 4 years and slowly progressed over the next 10 years. The stereotypical attack was characterized by choreoathetotic movements of all extremities and twisting of the trunk without loss of consciousness, usually precipitated by stress and fatigue (Video). Attacks occurred 2 to 3 times daily, lasting from several minutes to hours. The family history revealed similar symptoms in his mother, maternal grandmother, and aunt (Figure, A). He was completely healthy after birth and had normal intellectual and physical development. Treatment with carbamazepine and sodium valproate was not of sustained effectiveness.